(CNN) -- A federal judge on Tuesday granted a new trial for five former New Orleans police officers convicted in the Danziger Bridge case, citing prosecutorial misconduct.

"This Court is unaware of any case ... wherein prosecutors acting with anonymity used social media to circumvent ethical obligations, professional responsibilities, and even to commit violations of the Code of Federal regulations," U.S. District Justice Kurt D. Engelhardt said in the ruling.

The five were convicted in 2011 on a combined 25 counts of civil rights violations and were sentenced to prison terms ranging from six to 65 years for the shootings of unarmed civilians in the chaotic aftermath of Hurricane Katrina.

The shootings occurred on the Danziger Bridge on September 4, 2005, six days after much of New Orleans went under water when the powerful hurricane slammed into the Gulf Coast.